Hi

We have plans to make use of Jane Street's bin_prot-based RPC libraries
for some future projects, but one requirement is that we must
interoperate with clients written in other languages, namely PHP.

So I've been working on these 3 projects to make this possible:

* libbin_prot [1] is a C port of (most of) bin_prot, with added support
for RPC clients. This was written to avoid having to implement bin_prot
multiple times in other languages - one can just write bindings to the C
library.

* php-bin_prot [2] is a PHP extension binding libbin_prot. It supports
both PHP 5 and 7.

* ppx_bin_prot_interop [3] is a PPX rewriter that generates PHP code
from OCaml type definitions. It's written in a way that it should be
easy enough to add support for other languages, as it builds a
sort-of-AST that just has to be converted to strings in the proper
language syntax. It's a bit hackish but gets the job done. The
repository includes an example with an OCaml RPC server and a PHP client.

ppx_bin_prot_interop is not on OPAM yet because I'm relying on the
latest jbuilder version that is only available on Jane Street's
repository [4] as of now. You should still be able to use it via "opam
pin" if you want to give it a try.

[1] https://github.com/andrenth/libbin_prot
[2] https://github.com/andrenth/php-bin_prot
[3] https://github.com/andrenth/ppx_bin_prot_interop
[4] opam repo add janestreet
https://github.com/janestreet/opam-repository.git

Now that OCaml can talk to PHP, world domination should not be too far.

Cheers,
Andre